Flash arrester

ABSTRACT

For use in a welding system which uses combustible gases and the like, a flash arrester comprising a main body having an opening therethrough and including a frusto-conical seat, and a ball cage body positioned in the main body and having an axial opening therein. The ball cage body has a frusto-conical seat complementary to the first-mentioned seat of the main body. The other end of the ball cage body has axially extending slots to provide spaced axially extending fingers. The fingers have frusto-conical surfaces. A ball seat member is provided on the other end of the main body and has a frusto-conical ball seat. A ceramic ball is provided between the fingers and is freely movable between the second valve seat and the ball seat.

This is a continuation of application Ser. No. 874,807, filed Feb. 3,1978 which in turn is a continuation of application Ser. No. 710,861,filed Aug. 2, 1976, both now abandoned.

This invention relates to systems which use flammable gases such asoxygen and acetylene for welding and particularly to flash arresters forsuch systems.

BACKGROUND OF THE INVENTION

In systems which utilize flammable gases such as oxygen and acetylenefor welding as by a torch, one of the problems that may often occur isthat the flame tends to flash back toward the source of oxygen oracetylene. Accordingly, it has become necessary to interpose deviceswhich are in the nature of check valves in the lines that extend back tothe source. Such devices are commonly known as flash arresters.

Among the problems are that the flash arresters often utilize materialsthat are destroyed by the heat in the passage of the flame back towardthe source so the flash arrester is thereafter no longer effective. Thetemperatures encountered may be 1000° F. or more. For example, flasharresters utilize springs, rubber O-rings and the like, which aredestroyed. A more serious problem is that the operator often does notknow that there has been a flashback and the flash arrester has beendestroyed so that there is generally no warning that the flash arresteris no longer operable.

Accordingly, among the objects of the invention are to provide a flasharrester which is made and designed so that it will withstand thetemperatures involved without destruction so that it can be reusable;which can be operated at varying angles required; and which utilizes aminimum number of parts.

SUMMARY OF THE INVENTION

In accordance with the invention, the flash arrester comprises a mainbody having an opening therethrough and including a frusto-conical seatadjacent one end, and a ball cage body having an axial opening therein,and having a frusto-conical portion complementary to the first mentionedseat of said main body. The other end of the ball cage body has axiallyextending slots to provide spaced axially extending fingers. The openingthrough the ball cage body has a second frusto-conical seat on thefingers. A ball seat member is threaded into the other end of the mainbody, and has a frusto-conical ball seat. A ceramic ball is freelymovable within the fingers between the second valve seat and the ballseat.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partly diagrammatic view showing the invention applied to atypical welding system.

FIG. 2 is a fragmentary longitudinal sectional view on an enlarged scalethrough a flash arrester embodying the invention.

FIG. 3 is a sectional view of part of the valve arrester taken along theline 3--3 in FIG. 4.

FIG. 4 is a bottom end view of the part shown in the FIG. 3.

FIG. 5 is a side elevational view of another part of the flash arrester.

FIG. 6 is a side elevational view of a further part of the flasharrester.

DESCRIPTION

Referring to FIG. 1, in a typical welding system, torch 10 is suppliedwith flammable gases such as oxygen and acetylene through lines 11, 12from suitable sources, one of which is shown at 13. Flash arresters 15are interposed between the torch and the source. Alternatively, where adistributor block is utilized to supply the torch, the flash arresters15 may be provided between the distributor block and the source.

Referring to FIGS. 2-6, each flash arrester 15 comprises a main body 16that has an axial opening 17 therethrough. The upper end of the mainbody 16 is threaded as at 18 for engagement with a fitment 19 on thetorch or distributor body. The opening 17 is formed intermediate itsends with a frusto-conical seat 20 forming an angle of preferably 30°with the axis of the opening 19.

A cage element or body 21 is inserted in the opening 17 and hassubstantially the same diameter as the lower portion of the opening 17.The cage element 21 includes a frusto-conical end portion or surface 22that has the same angle as the valve seat 20 and is adapted to engagethe valve seat 20. The lower end of the cage element is provided withaxial slots 23 forming fingers 24 and an opening 25 extends through themember 21. The lower end 26 of opening 25 adjacent the fingers 24 isenlarged and connected to the upper end of the opening 25 by afrusto-conical surface 27 on each finger.

The lower end of the main body 15 (FIG. 2) is threaded as at 28 toreceive the upper end of a ball seat member 29 that has a frusto-conicalball seat 30. A ceramic ball 31 is provided in the area between thefingers 24 and the seat 30. The seat member 29 includes an axial opening32 extending from the seat through the member 29. The lower end of theseat member 29 is threaded as at 33 to receive the fitment 34 of asupply hose or the like. A screen 35 is provided adjacent a shoulder 36in the lower end of the opening 29 and is held therein by a snap ring37.

Each finger 24 includes an external radial shoulder 38 which is engagedby the end 39 of ball seat member 29.

The ball 31 is made of a ceramic material such as aluminum oxide havingthe following mechanical properties:

    ______________________________________                                        Tensile Strength (77° F.)                                                                    28,000 psi                                              Tensile Strength (1832° F.)                                                                  15,000 psi                                              Compressive Strength (77° F.)                                                                330,000 psi                                             Compressive Strength (1832° F.)                                                              140,000 psi                                             Hardness (Rockwell)   45 N 81                                                 Modulus of Elasticity 52,000,000 psi                                          Density               0.139 lb./in..sup.3                                     Specific Gravity      3.80-3.84                                               Maximum Useful Temp   3180° F.                                         Water Absorption      Nil                                                     Magnetic Properties   Non-Magnetic                                            ______________________________________                                    

The ball diameter is preferably 1.5 times the orifice diameter formed byopening 25. The area formed by the slots 23 is preferably 25--35% lessthan the orifice area.

The ball is preferably made within a tolerance of ±0.0001.

The distance between the inclined surfaces 27 of the ball cage elementand the ends of the fingers 24 is such that the bottom of the ball 31 isflush with the end of the cage element 21 when the ball is againstsurfaces 27.

The various parts of the flash arrester except for the ball are made ofa metal which is capable of withstanding the temperatures involved suchas aluminum, yellow brass or stainless steel. The screen is preferablymade of stainless steel and the retaining ring is preferably made ofstainless steel wire.

In use, the normal movement of the torch will not be adversely affectedby movement of the ball 31 since the ball 31 is made of such lightweightmaterial that it will not interfere with the flow of gases toward thetorch. In other words, the pressure of gases is sufficient to keep theball away from the valve seat 30.

However, should a flashback occur, the ball 31 is immediately movedtoward the valve seat 30 preventing flame from passing toward thesource. When the torch is again used, the flash arrester will continueto be effective since none of the parts will have been adverselyaffected by the high temperature of the flashback.

In a typical flash arrester, the following dimensions have been found tobe effective:

    ______________________________________                                        Ball diameter        .3750                                                    Angle of ball seat 20                                                                              30°                                               Angle of ball seat 22                                                                              30°                                               Angle of ball seat 30                                                                              30°                                               Diameter of opening  .25                                                      ______________________________________                                    

In describing the flash arrester, terms such as "top", "bottom" and thelike have been utilized and it should be understood that these aremerely terms of description and not limitation.

I claim:
 1. For use in a system where combustible gases are utilized asin welding and the like, a flash arrester comprising an assembly of (1)a main body, (2) a ball cage body, (3) a ball seat member and (4) aceramic ball,said main body having an opening extending axiallytherethrough and including an uninterrupted frusto-conical seatintermediate first and second opposite axial ends of said opening, saidmain body having said opposite axial ends of said opening threaded, saidball cage body having an axial opening therein, said ball cage bodybeing inserted into said through opening of said main body via saidsecond end thereof with a close fit and having an uninterruptedfrusto-conical surface at one end complementary to and engaging thefirst-mentioned frusto-conical seat of said main body, the other end ofsaid ball cage body having axially extending slots to provide spacedaxially extending fingers, each said finger having a frusto-conicalsurface adjacent the base thereof defining a first ball seat interruptedby spaces formed by said slots, said ball seat member having externalthreads on a first end thereof threaded into the threaded opening insaid second end of said main body, an uninterrupted frusto-conicalsurface adjacent said first end of said ball seat member defining asecond ball seat, said ball seat member having an opening extendingaxially therethrough between said first end thereof and a second endthereof axially opposite said first end of said ball seat member, saidmain body, ball cage body, and ball seat member being made of a materialcapable of withstanding welding flame temperatures, each said finger ofsaid ball cage member having a shoulder spaced from the free endsthereof extending radially to the periphery thereof, said first end ofsaid ball seat member engaging said shoulder when threaded into saidsecond end of said body for forcing said uninterrupted frusto-conicalsurface of said ball cage body into tight engagement with saidfirst-mentioned frusto-conical seat of said main body, said ceramic ballhaving substantially the same diameter as the diameter of the openingadjacent said fingers, the interior space between said first and secondball seats being empty except for said ceramic ball such that saidceramic ball is freely movable axially between said second and firstball seats to thereby function as a lightweight, wear and flameresistance flash arresting back check valve without the use of a valvebiasing spring, said opening through said ball seat member including acounterbore having an enlarge diameter adjacent said second end of saidball seat member, said assembly further including a screen interposed insaid counterbore, and a retaining ring holding said screen in positionin said counterbore, said screen and ring being made of a materialcapable of withstanding welding temperatures.
 2. The flash arrester setforth in claim 1 wherein said ball is made of aluminum oxide.
 3. Theflash arrester set forth in claim 2 wherein said ball is made of amaterial having the following mechanical properties:

    ______________________________________                                        Tensile Strength (77° F.)                                                                    28,000 psi                                              Tensile Strength (1832° F.)                                                                  15,000 psi                                              Compressive Strength (77° F.)                                                                330,000 psi                                             Compressive Strength (1832° F.)                                                              140,000 psi                                             Hardness (Rockwell)   45 N 81                                                 Modulus of Elasticity 52,000.000 psi                                          Density               0.139 lb./in..sup.3                                     Specific Gravity      3.80-3.84                                               Maximum Useful Temp   3180° F.                                         Water Absorption      Nil                                                     Magnetic Properties   Non-Magnetic                                            ______________________________________                                    